U.S. patent application number 12/498871 was filed with the patent office on 2011-01-13 for parallel optical communications device having weldable inserts.
This patent application is currently assigned to Avago Technologies Fiber IP (Singapore) Pte. Ltd.. Invention is credited to Ye Chen, Ron Kaneshiro, David J.K. Meadowcroft, Hui Xu.
Application Number | 20110008005 12/498871 |
Document ID | / |
Family ID | 43308010 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110008005 |
Kind Code |
A1 |
Meadowcroft; David J.K. ; et
al. |
January 13, 2011 |
PARALLEL OPTICAL COMMUNICATIONS DEVICE HAVING WELDABLE INSERTS
Abstract
A parallel optical communications device is provided that has an
OSA that includes at least one heat dissipation block having a slot
formed in a lower surface thereof that contains a weldable insert.
Likewise, an upper surface of the mounting device of the ESA has at
least one slot formed therein that contains a weldable insert.
After the OSA is placed in contact with the ESA and optically
aligned with the ESA, the OSA is secured to the upper surface of
the mounting device of the ESA by welding together the respective
weldable inserts contained in the respective slots in the OSA and
in the mounting device of the ESA. The welding process results in
an extremely strong welded joint between the OSA and the ESA that
prevents relative movement between the OSA and the ESA if external
forces that are exerted on the OSA and/or on the ESA.
Inventors: |
Meadowcroft; David J.K.;
(San Jose, CA) ; Xu; Hui; (Santa Clara, CA)
; Chen; Ye; (San Jose, CA) ; Kaneshiro; Ron;
(Los Altos, CA) |
Correspondence
Address: |
Kathy Manke;Avago Technologies Limited
4380 Ziegler Road
Fort Collins
CO
80525
US
|
Assignee: |
Avago Technologies Fiber IP
(Singapore) Pte. Ltd.
Singapore
SG
|
Family ID: |
43308010 |
Appl. No.: |
12/498871 |
Filed: |
July 7, 2009 |
Current U.S.
Class: |
385/88 ;
228/135 |
Current CPC
Class: |
G02B 6/4246
20130101 |
Class at
Publication: |
385/88 ;
228/135 |
International
Class: |
G02B 6/36 20060101
G02B006/36; B23K 31/02 20060101 B23K031/02 |
Claims
1. A parallel optical communications device comprising: a
substrate; an electrical subassembly (ESA) mounted on the
substrate, the mounting device having at least an upper surface and
a lower surface, the upper surface of the mounting device having at
least one integrated circuit (IC) and a plurality of active optical
devices mounted thereon, said at least one IC being electrically
coupled to the active optical devices, said at least one IC being
electrically coupled to electrical conductors of the substrate, the
mounting device having at least one slot formed in the upper
surface of the mounting device and at least one weldable ESA insert
contained in said at least one slot; an optical subassembly (OSA)
mechanically coupled to the ESA, the OSA including at least one
heat dissipation block secured thereto, said at least one heat
dissipation block comprising a material having a high thermal
conductivity, said at least one heat dissipation block having at
least one slot formed therein in a lower surface of said at least
one heat dissipation block and at least one weldable OSA insert
contained in said at least one slot formed in the lower surface of
said at least one heat dissipation block, the lower surface of said
at least one heat dissipation block being in at least partial
contact with the upper surface of the mounting device such that the
weldable OSA and ESA inserts are at least partially in contact with
one another; and wherein said at least one weldable ESA insert and
said at least one weldable OSA insert are welded together to form
at least one welded joint between the OSA and the ESA, and wherein
said at least one welded joint is structurally very strong to
prevent relative movement from occurring between the OSA and the
ESA.
2. The parallel optical communications device of claim 1, wherein
the mounting device has at least two slots formed therein at
opposite ends of the mounting device, each of the slots containing
the weldable ESA insert, and wherein the OSA includes at least two
heat dissipation blocks secured to opposite sides of the OSA, each
of the heat dissipation blocks having a slot formed in the lower
surface thereof with each slot formed in the lower surfaces of the
heat dissipation blocks containing the weldable OSA insert, and
wherein when the OSA and the ESA are mechanically coupled together,
the weldable OSA inserts are in contact with respective ones of the
weldable ESA inserts, and wherein the weldable ESA inserts and the
respective weldable OSA inserts are welded together to form said at
least one welded joint between the OSA and the ESA.
3. The parallel optical communications device of claim 1, wherein
said at least one weldable OSA insert has a lower surface that is
generally co-planar with the lower surface of said at least one
heat dissipation block, and wherein the lower surface of said at
least one weldable OSA insert has a surface area that is relatively
small compared to a surface area of the lower surface of said at
least one heat dissipation block.
4. The parallel optical communications device of claim 3, wherein
the surface area of the lower surface of said at least one weldable
OSA insert is no greater than about 50% of the surface area of the
lower surface of said at least one heat dissipation block.
5. The parallel optical communications device of claim 4, wherein
the surface area of the lower surface of said at least one weldable
OSA insert is less than or equal to about 35% of the surface area
of the lower surface of said at least one heat dissipation
block.
6. The parallel optical communications device of claim 1, wherein
said at least one slot formed in the lower surface of said at least
one heat dissipation block is smaller in a width dimension than a
width dimension of said at least one slot formed in the upper
surface of the mounting device, and wherein said at least one
weldable OSA insert is smaller in a width dimension than a width
dimension of said at least one weldable ESA insert such that a step
exists where the weldable OSA insert and the weldable ESA insert
meet.
7. The parallel optical communications device of claim 1, wherein
said at least one slot formed in the lower surface of said at least
one heat dissipation block is greater in a width dimension than a
width dimension of said at least one slot formed in the upper
surface of the mounting device, and wherein said at least one
weldable OSA insert is greater in at least a width dimension than a
width dimension of said at least one weldable ESA insert such that
a step exists where the weldable OSA insert and the weldable ESA
insert meet.
8. A parallel optical communications device comprising: a substrate
having one or more electrical conductors passing through the
substrate; an electrical subassembly (ESA) mounted on the
substrate, the mounting device having at least an upper surface and
a lower surface, the upper surface of the mounting device having at
least one integrated circuit (IC) and a plurality of active optical
devices mounted thereon, said at least one IC being electrically
coupled to the active optical devices, said at least one IC being
electrically coupled to one or more of the electrical conductors of
the substrate, the mounting device having at least two slots formed
in the upper surface of the mounting device at opposite ends
thereof, each of the slots containing a weldable ESA insert; an
optical subassembly (OSA) mechanically coupled to the ESA, the OSA
including at least two heat dissipation block secured thereto on
opposite ends thereof, said at least two heat dissipation blocks
comprising a material of high thermal conductivity, each heat
dissipation block having at least one slot formed in a lower
surface thereof and a weldable OSA insert contained in each slot
formed in the lower surfaces of the heat dissipation blocks, the
lower surfaces of the heat dissipation blocks being in at least
partial contact with the upper surface of the mounting device such
that the weldable OSA inserts are at least partially in contact
with respective ones of the weldable ESA inserts; and wherein
respective ones of the weldable ESA inserts are welded to
respective ones of the weldable OSA inserts to form at least two
welded joints between the OSA and the ESA, and wherein said at
least two welded joints are structurally very strong to prevent
relative movement from occurring between the OSA and the ESA.
9. The parallel optical communications device of claim 8, wherein
the weldable OSA inserts have respective lowers surfaces that are
generally co-planar with the respective lower surfaces of the
respective heat dissipation blocks, and wherein the respective
lower surfaces of the respective weldable OSA inserts have
respective surfaces area that are relatively small compared to the
respective surface areas of the respective lower surfaces of the
respective heat dissipation blocks.
10. The parallel optical communications device of claim 9, wherein
the surface areas of the lower surfaces of the weldable OSA inserts
are no greater than 50% of the respective surface areas of the
respective lower surfaces of the respective heat dissipation
blocks.
11. The parallel optical communications device of claim 10, wherein
the surface areas of the lower surfaces of the respective weldable
OSA inserts are less than or equal to about 35% of the respective
surface areas of the respective lower surfaces of the respective
heat dissipation blocks.
12. The parallel optical communications device of claim 9, wherein
the respective slots formed in the respective lower surfaces of the
respective heat dissipation blocks are smaller in a width dimension
than a width dimension of the respective slots formed in the upper
surface of the mounting device, and wherein the respective weldable
OSA inserts are smaller in a width dimension than a width dimension
of the respective weldable ESA inserts such that respective steps
exists where the respective weldable OSA inserts and the respective
weldable ESA inserts meet.
13. The parallel optical communications device of claim 9, wherein
the respective slots formed in the respective lower surfaces of the
respective heat dissipation blocks are greater in a width dimension
than a width dimension of the respective slots formed in the upper
surface of the mounting device, and wherein the respective weldable
OSA inserts are greater in a width dimension than a width dimension
of the respective weldable ESA inserts such that respective steps
exists where the respective weldable OSA inserts and the respective
weldable ESA inserts meet.
14. A method for securing an electrical subassembly (ESA) of a
parallel optical communications device to an optical subassembly
(OSA) of the parallel optical communications device, the method
comprising: mounting a mounting device of an ESA on a substrate,
the mounting device having at least an upper surface and a lower
surface, the upper surface of the mounting device having at least
one integrated circuit (IC) of the ESA and a plurality of active
optical devices of the ESA mounted thereon, said at least one IC
being electrically coupled to the active optical devices, said at
least one IC being electrically coupled to electrical conductors of
the substrate, the mounting device having at least one slot formed
in the upper surface of the mounting device and at least one
weldable ESA insert contained in said at least one slot;
mechanically coupling an OSA to the ESA, the OSA including at least
one heat dissipation block secured thereto, said at least one heat
dissipation block comprising a material having a high thermal
conductivity, said at least one heat dissipation block having at
least one slot formed therein in a lower surface of said at least
one heat dissipation block and at least one weldable OSA insert
contained in said at least one slot formed in the lower surface of
said at least one heat dissipation block, the lower surface of said
at least one heat dissipation block being in at least partial
contact with the upper surface of the mounting device such that the
weldable OSA and ESA inserts are at least partially in contact with
one another; and optically aligning the OSA to the ESA; and welding
said at least one weldable ESA insert and said at least one
weldable OSA insert together to form at least one welded joint
between the OSA and the ESA, and wherein said at least one welded
joint is structurally very strong to prevent relative movement from
occurring between the OSA and the ESA.
15. The method of claim 14, wherein said at least one weldable OSA
insert has a lower surface that is generally co-planar with the
lower surface of said at least one heat dissipation block, and
wherein the lower surface of said at least one weldable OSA insert
has a surface area that is relatively small compared to a surface
area of the lower surface of said at least one heat dissipation
block.
16. The method of claim 15, wherein the surface area of the lower
surface of said at least one weldable OSA insert is no greater than
50% of the surface area of the lower surface of said at least one
heat dissipation block.
17. The method of claim 16, wherein the surface area of the lower
surface of said at least one weldable OSA insert is less than or
equal to about 35% of the surface area of the lower surface of said
at least one heat dissipation block.
18. The method of claim 14, wherein said at least one slot formed
in the lower surface of said at least one heat dissipation block is
smaller in a width dimension than a width dimension of said at
least one slot formed in the upper surface of the mounting device,
and wherein said at least one weldable OSA insert is smaller in a
width dimension than a width dimension of said at least one
weldable ESA insert such that a step exists where the weldable OSA
insert and the weldable ESA insert meet.
19. The method of claim 14, wherein said at least one slot formed
in the lower surface of said at least one heat dissipation block is
greater in a width dimension than a width dimension of said at
least one slot formed in the upper surface of the mounting device,
and wherein said at least one weldable OSA insert is greater in at
least a width dimension than a width dimension of said at least one
weldable ESA insert such that a step exists where the weldable OSA
insert and the weldable ESA insert meet.
20. A method for securing an electrical subassembly (ESA) of a
parallel optical communications device to an optical subassembly
(OSA) of the parallel optical communications device, the method
comprising: mounting a mounting device of an ESA on a substrate,
the substrate having one or more electrical conductors passing
through the substrate, the mounting device having at least an upper
surface and a lower surface, the upper surface of the mounting
device having at least one integrated circuit (IC) of the ESA and a
plurality of active optical devices of the ESA mounted thereon,
said at least one IC being electrically coupled to the active
optical devices, said at least one IC being electrically coupled to
one or more of the electrical conductors of the substrate, the
mounting device having at least two slots formed in the upper
surface thereof at opposite ends thereof, each of the slots
containing a weldable ESA insert; mechanically coupling an OSA to
the ESA, the OSA including at least two heat dissipation block
secured thereto on opposite ends thereof, said at least two heat
dissipation blocks comprising a material of high thermal
conductivity, each heat dissipation block having at least one slot
formed in a lower surface thereof and a weldable OSA insert
contained in each slot formed in the lower surfaces of the heat
dissipation blocks, the lower surfaces of the heat dissipation
blocks being in at least partial contact with the upper surface of
the mounting device such that the weldable OSA inserts are at least
partially in contact with respective ones of the weldable ESA
inserts; optically aligning the OSA with the ESA; and welding
respective ones of the weldable ESA inserts to respective ones of
the weldable OSA inserts to form at least two welded joints between
the OSA and the ESA, and wherein said at least two welded joints
are structurally very strong to prevent relative movement from
occurring between the OSA and the ESA.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The invention relates to parallel optical communications
devices such as parallel optical transmitters, receivers, and
transceivers. More particularly, the invention relates to a
parallel optical communications device having weldable inserts that
enable parts of the device to be secured to each other in a way
that ensures that there will be no relative movement between the
parts, while still allowing the device to have good heat
dissipation characteristics.
BACKGROUND OF THE INVENTION
[0002] A variety of parallel optical communications devices exist
for simultaneously transmitting and/or receiving multiple optical
data signals over multiple respective optical data channels.
Parallel optical transmitters have multiple optical transmit
channels for transmitting multiple respective optical data signals
simultaneously over multiple respective optical waveguides (e.g.,
optical fibers). Parallel optical receivers have multiple optical
receive channels for receiving multiple respective optical data
signals simultaneously over multiple respective optical waveguides
(e.g., optical fibers). Parallel optical transceivers have multiple
optical transmit channels and multiple optical receive channels for
transmitting and receiving multiple respective optical transmit and
receive data signals simultaneously over multiple respective
transmit and receive optical waveguides (e.g., optical fibers).
[0003] For each of these different types of parallel optical
communications devices, a variety of different designs and
configurations exist. A typical layout for a parallel optical
communications device includes a first mounting device, such as a
printed circuit board (PCB), a flex circuit, or a leadframe, which
is used to mount a plurality of active optical devices (e.g., laser
diodes and/or photodiodes) and one or more integrated circuits
(ICs) (e.g., a laser diode driver IC, a receiver IC, a controller
IC). The combination of these electrical components and the first
mounting device on which they are mounted is typically referred to
as the electrical subassembly (ESA). A second circuit board, such
as a PCB, a ball grid array (BGA), or the like, that is external to
the parallel optical communications device, is used for mounting
one or more other ICs and other electrical components. The second
circuit board and the first mounting device are electrically
connected to each other to provide electrical connections between
the electrical components of the ESA and the electrical components
mounted on the second circuit board.
[0004] Similar configurations are used for parallel optical
receivers, except that the ESA has a plurality of photodiodes
instead of laser diodes and a receiver IC instead of a laser diode
driver IC. An ESA of a parallel optical transceiver typically has
laser diodes, photodiodes, a laser driver diode IC, and a receiver
IC, although one or more of these devices may be integrated into
the same IC to reduce part count and to provide other benefits.
[0005] A typical parallel optical communications device also
includes an optical subassembly (OSA), which holds optical elements
for coupling light between the laser diodes and/or photodiodes of
the ESA and the ends of respective optical fibers that are held
within a connector that mechanically couples with the OSA. The OSA
is secured to the ESA. There are sometimes mating features on the
OSA and on the ESA that allow the OSA to be coupled to the ESA in a
way that limits movement of the OSA relative to the mounting device
to provides some degree of coarse alignment between the optical
elements of the OSA and the laser diodes and/or photodiodes of the
ESA. Prior to coupling the OSA to the ESA, an adhesive material,
such as epoxy, for example, is placed at one or more locations on
one or more surfaces of the OSA and/or of the ESA. After the OSA
has been coupled to the mounting device, and prior to the adhesive
material hardening, an alignment process is typically used during
which relative movement between the OSA and the ESA is produced
until a determination is made that the optical elements of the OSA
are precisely aligned with the laser diodes and/or photodiodes of
the ESA. The OSA and the ESA are then tightly held in the aligned
position until the adhesive material has been cured and otherwise
hardens.
[0006] There are several challenges associated with coupling the
OSA to the ESA, precisely optically aligning the OSA with the laser
diodes and/or photodiodes of the ESA, and securing the OSA to the
ESA in the precisely aligned position. In order to manufacture the
parallel optical communications modules with high volume, the OSA
must be coupled, precisely aligned, and secured to the OSA very
quickly, e.g., in less than one minute. In addition, after the OSA
has been secured to the ESA, very little or no movement of the OSA
and ESA relative to each other should occur over the life of the
parallel optical communications device, or else the precise optical
alignment may be lost. Precise optical alignment is critical to
having good signal integrity, and thus good overall performance.
Often times, a customer attaches a heat sink device to the parallel
optical communications device, which causes forces to be exerted on
the OSA and/or on the ESA. If the bond that is formed by the
adhesive material is not sufficiently strong, the exertion of such
forces over months or years can result in very slow movement of the
OSA and ESA relative to each other, sometimes referred to as
creeping. Of course, such movement can result in the precise
alignment needed being lost, resulting in a degradation in
performance.
[0007] In addition to the issues associated with aligning the OSA
with the ESA and securing them together, heat dissipation is a
major consideration in parallel optical communications devices. In
the aforementioned parallel optical communications devices, some
portion or portions of the mounting device of the ESA has one or
more heat sink devices thereon that dissipate heat generated by the
electrical components of the ESA. Often times, the customer
provides its own heat sink device, which the customer secures to
the mounting device of the ESA. The heat sink device is typically
secured to the mounting device of the ESA by a thermally conductive
epoxy material. One of the problems associated with securing the
heat sink device to the ESA is that the customer typically exerts a
relatively large force on the heat sink device during this process,
which, in turn, is exerted on the ESA. Components of this force may
also be exerted on the OSA. Such forces can result in movement of
the OSA and the ESA relative to each other, which can result in the
precise alignment between the OSA and the ESA being lost.
[0008] The aforementioned heat sink devices have various shapes or
configurations, but have the same general purpose of receiving heat
generated by the ICs and active optical devices of the ESA and
absorbing and/or spreading out the heat such that the heat is moved
away from the ICs and active optical devices. Heat generated by the
ICs can detrimentally affect the performance of the parallel
optical communications device. For example, in parallel optical
transmitters and transceivers, the laser diode driver ICs generate
very large amounts of heat in producing the high speed signals that
drive the laser diodes. If adequate measures to dissipate this heat
are not taken, the heat can detrimentally affect the performance of
the laser diode ICs, which are typically placed in relatively close
proximity to the laser diode driver IC. Heat dissipation
considerations are even more important in parallel optical
communications device due to the large number of channels and
associated electrical circuitry.
[0009] In addition, there is an ever-increasing need to decrease
the size of parallel optical communications devices and to increase
the number of channels in parallel optical communications devices.
In order to meet these needs, the layout of a parallel optical
communications device should be efficient in terms of space
utilization, highly effective at dissipating heat, and protective
of signal integrity. As the number of channels and the associated
electrical components increases, the amount of heat that must be
dissipated also increases, which emphasizes the need for a highly
effective heat dissipation configuration. Also, as the dimensions
of the parallel optical communications device decrease, the space
between the electrical components decreases. This reduced space
between components also emphasizes the need for a highly effective
heat dissipation configuration in order to prevent heat generated
by one component from detrimentally affecting another.
[0010] In addition to the need for highly effective heat
dissipation configurations in parallel optical communications
devices, the OSA should be secured to the ESA in a way that ensures
that there will be no movement of the OSA and ESA relative to each
other. In general, parallel optical communications devices are
non-hermetically, or semi-hermetically, sealed devices. As
indicated above, typically, an adhesive material such as epoxy is
used to secure the OSA to the ESA while the OSA and the ESA are
held in tight alignment. This adhesive bond tends to be
structurally weak, which can result in movement of the OSA and the
ESA relative to each other. Likewise, as indicated above, an
adhesive material such as a thermally conductive epoxy is often
used to secure the heat sink device to the mounting device of the
ESA. This adhesive bond is also relatively structurally weak, which
can result in movement of the heat sink device and the ESA relative
to each other. As indicate above, such movement can result in
forces being exerted on the OSA, resulting in movement of the OSA
and the ESA relative to each other. Such movement can, as indicated
above, result in the precise optical alignment between the OSA and
the ESA being lost, which can result in a degradation in signal
quality.
[0011] Accordingly, a need exists for a parallel optical
communications device that is configured with an extremely strong
bond between the OSA and the mounting device of the ESA to prevent
any movement between OSA and the ESA, and which does not impede the
heat dissipation qualities of the parallel optical communications
device. A need also exists for a method for quickly aligning and
securing the OSA to the mounting device of the ESA in a way that
creates an extremely strong bond at the interface between the OSA
and the ESA mounting surface and that enables very precise optical
alignment to be achieved between the OSA and the ESA.
SUMMARY OF THE INVENTION
[0012] The invention is directed to a parallel optical
communications device and to a method. The parallel optical
communications device comprises a substrate, an electrical
subassembly (ESA) mounted on the substrate, and an optical
subassembly (OSA) mechanically coupled to the ESA. The ESA includes
a mounting device having at least an upper surface and a lower
surface. The upper surface of the mounting device has at least one
IC and a plurality of active optical devices mounted thereon. The
IC is electrically coupled the active optical devices and to one or
more electrical conductors of the substrate. The mounting device
has at least one slot formed in the upper surface thereof and at
least one weldable ESA insert contained in the slot. The OSA
includes at least one heat dissipation block secured thereto
comprising a material having a high thermal conductivity. The heat
dissipation block has at least one slot formed in a lower surface
thereof and at least one weldable OSA insert contained in the slot.
The lower surface of the heat dissipation block is in at least
partial contact with the upper surface of the mounting device such
that the weldable OSA and ESA inserts are at least partially in
contact with one another. The weldable ESA insert and the weldable
OSA insert are welded together to form at least one welded joint
between the OSA and the ESA. The welded joint is structurally very
strong to prevent relative movement from occurring between the OSA
and the ESA, even if external forces are exerted on the ESA and/or
the OSA.
[0013] In accordance with another embodiment of the parallel
optical communications device, the mounting device has at least two
slots formed in the upper surface thereof at opposite ends of the
mounting device, with each slot having at least one weldable ESA
insert contained therein. The OSA includes at least two heat
dissipation blocks secured to opposite ends thereof comprising a
material having a high thermal conductivity. The heat dissipation
blocks have at least one slot formed in the lower surfaces thereof
and respective weldable OSAs contained in the respective slots. The
lower surfaces of the heat dissipation blocks are in at least
partial contact with the upper surface of the mounting device such
that the respective weldable OSA inserts and the respective ESA
weldable inserts are at least partially in contact with one
another. The respective weldable ESA inserts and the respective
weldable OSA inserts are welded together to form at least two
welded joints between the OSA and the ESA. The welded joints are
structurally very strong to prevent relative movement from
occurring between the OSA and the ESA, even if external forces are
exerted on the ESA and/or on the OSA.
[0014] The method for securing an ESA of a parallel optical
communications device to an OSA of the parallel optical
communications device comprises mounting a mounting device of an
ESA on a substrate, mechanically coupling an OSA to the ESA,
optically aligning the OSA to the ESA, and welding a weldable ESA
insert contained in a slot formed in the upper surface of the
mounting device together with a weldable OSA insert contained in a
slot formed in the upper surface of a heat dissipation block of the
OSA to form a welded joint between the OSA and the ESA. The welded
joint is structurally very strong to prevent relative movement from
occurring between the OSA and the ESA, even if external forces are
exerted on the ESA and/or on the OSA.
[0015] In accordance with another embodiment, the method for
securing an ESA of a parallel optical communications device to an
OSA of the parallel optical communications device comprises
mounting a mounting device of an ESA on a substrate, mechanically
coupling an OSA to the ESA, optically aligning the OSA to the ESA,
and welding the weldable ESA insert and the weldable OSA insert
together to form at least one welded joint between the OSA and the
ESA. In accordance with this embodiment, at least two slots are
formed in the upper surface of the mounting device at opposite ends
thereof, with each slot having a weldable ESA insert contained
therein. The OSA includes at least two heat dissipation blocks
secured to opposite ends thereof comprising a material having a
high thermal conductivity. The heat dissipation blocks each have at
least one slot formed in the lower surface thereof and respective
weldable OSAs that are contained in the respective slots. The lower
surfaces of the heat dissipation blocks are in at least partial
contact with the upper surface of the mounting device such that the
respective weldable OSA inserts and the respective ESA weldable
inserts are at least partially in contact with one another. The
welded joints between the OSA and the ESA are structurally very
strong to prevent relative movement from occurring between the OSA
and the ESA, even if external forces are exerted on the ESA and/or
the OSA.
[0016] These and other features and advantages of the invention
will become apparent from the following description, drawings and
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 illustrates a perspective view of the lower portion
of a parallel optical communications device, which includes the ESA
mounted on a substrate and having a bond wire protector attached
thereto.
[0018] FIGS. 2A and 2B illustrate perspective top and bottom views,
respectively, of the OSA of the parallel optical communications
device in accordance with an embodiment, which is designed to
mechanically couple to the portion of the parallel optical
communications device shown in FIG. 1.
[0019] FIG. 3 illustrates a perspective top view of the parallel
optical transmitter of the invention in accordance with an
illustrative embodiment, which comprises the OSA shown in FIGS. 2A
and 2B secured to the ESA shown in FIG. 1.
[0020] FIG. 4 illustrates a top perspective view of the mounting
device shown in FIG. 3.
[0021] FIG. 5 illustrates an exploded view of a portion of the side
of the parallel optical transmitter 110 shown in FIG. 3.
[0022] FIG. 6 illustrates a perspective bottom view of the heat
dissipation block of the parallel optical transmitter 110 shown in
FIG. 3 in accordance with an embodiment in which the weldable
inserts may have resistive features on them to allow for resistive
welding to be used to weld the inserts together.
[0023] FIG. 7 illustrates an exploded view of a portion of the side
of the parallel optical transmitter shown in FIG. 3, which
demonstrates the manner in which a solder material placed on a step
where the weldable inserts of the ESA and the OSA meet and used to
weld the inserts together.
[0024] FIG. 8 illustrates a perspective view of a cross-section of
the parallel optical transmitter shown in FIG. 3, which
demonstrates the manner in which a laser welding technique may be
used to weld the weldable inserts shown in FIG. 3 together.
DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT
[0025] In accordance with the invention, a parallel optical
communications device is provided that has an OSA that includes at
least one heat dissipation block having a slot formed in a lower
surface thereof that contains a weldable insert. Likewise, an upper
surface of the mounting device of the ESA has at least one slot
formed therein that contains a weldable insert. After the OSA has
been placed in contact with the ESA and optically aligned with the
ESA, the OSA is secured to the upper surface of the mounting device
of the ESA by welding together the weldable inserts contained in
the slots in the OSA and in the slots formed in the mounting device
of the ESA. The welding process results in an extremely strong
welded joint being formed between the OSA and the ESA that prevents
relative movement between the OSA and the ESA. In this way, any
forces that are exerted on the parallel optical communications
device temporarily or over its lifetime will not cause the precise
optical alignment of the OSA and the ESA to be compromised. In
addition, the weldable inserts are small in size compared to the
dimensions of the lower surface of the heat dissipation block and
the upper surface of the ESA mounting device to ensure that the
inserts do not block the heat dissipation pathways from the ESA
mounting device into and through the heat dissipation block.
[0026] FIG. 1 illustrates a perspective view of the lower portion
of a parallel optical communications device, which includes the ESA
1 mounted on a substrate 20 and having a bond wire protector 30
attached thereto. The bond wire protector 30 includes first and
second bond wire protector devices 30A and 30B, as will be
described below in more detail. In accordance with this embodiment,
the parallel optical communications device is a parallel optical
transmitter. However, it should be noted that the parallel optical
communications device of the invention may instead be a parallel
optical receiver or a parallel optical transceiver. In the interest
of brevity, illustrative embodiments of the invention will be
described with reference to a parallel optical transmitter. Those
of ordinary skill in the art will understand the manner in which
the principles and concepts described herein in relation to the
parallel optical transmitter described herein with reference to the
drawings can be applied to parallel optical receivers and parallel
optical transceivers.
[0027] The ESA 1 includes a mounting device 10 and the core
electrical components 2, 3 and 4 of the parallel optical
transmitter. The mounting device 10 serves as a mounting core for
mounting at least the core electrical components of the parallel
optical transmitter. In accordance with this embodiment, the core
electrical components of the ESA 1 include a first laser diode
driver IC 2, a second laser diode driver IC 3, and a vertical
cavity surface emitting laser (VCSEL) IC 4. The laser diode driver
ICs 2 and 3 and the VCSEL IC 4 are mounted on an upper surface 10A
of the mounting device 10. The laser diode driver ICs 2 and 3 are
electrically connected to the VCSEL IC 4 by electrical conductors
(not shown), such as bond wires, to enable electrical control
signals and other electrical signals to be sent from the laser
diode driver ICs 2 and 3 to the VCSEL IC 4. The VCSEL IC 4 has a
plurality of VCSEL laser diodes 5 that produce a plurality of
respective optical data signals based on the electrical control
signals and respective electrical data signals provided to the
VCSEL IC 4 by the laser diode driver ICs 2 and 3. The electrical
control signals control the bias and modulation currents of the
VCSEL laser diodes 5.
[0028] In the illustrative embodiment shown in FIG. 1, the laser
diode driver ICs 2 and 3 and the VCSEL IC 4 are arranged in a
balanced laser driver layout on the upper surface 10A of the
mounting device 10. In the balanced laser driver layout, half of
the laser diodes 5 of the VCSEL IC 4 are driven by laser diode
driver IC 2 and the other half of the laser diodes 5 of the VCSEL
IC 4 are driven by laser diode driver IC 3. Because each of the
laser diode driver ICs 2 and 3 drives a subset of the total number
of laser diodes 5, the pitch (i.e., distance) between the
high-speed signal pathways within the laser diode driver ICs can be
increased. Increasing the pitch between the high-speed signal
pathways provides several advantages. One advantage of the
increased pitch is that it reduces the potential for electrical
cross-talk and inductive coupling between adjacent wire bonds that
connect the output driver pads on the driver IC to the respective
input pads on the laser diode IC. Reducing the potential for
electrical cross-talk and inductive coupling between these wire
bonds helps ensure high signal integrity.
[0029] Another advantage of the increased pitch is that the reduced
potential for electrical cross-talk and inductive coupling makes it
possible to mount the driver ICs 2 and 3 in closer proximity to the
laser diode IC 4 than would otherwise be possible. Mounting the
driver ICs 2 and 3 in closer proximity to the laser diode IC 4
allows the lengths of the wire bonds between the driver ICs 2 and 3
and the laser diode IC 4 to be reduced, which further reduces the
potential for electrical cross-talk and inductive coupling between
adjacent wire bonds.
[0030] While the balanced laser driver layout shown in FIG. 1
provides several advantages, it should be noted that it is not
necessary to use the balanced laser driver layout shown in FIG. 1.
The ICs and any other components that are mounted on the upper
surface 10A of the mounting device 10 may be arranged in any
desired layout. For example, the laser diode driver IC 2 could be
used to drive all of the laser diodes 5 of the VCSEL IC 4, in which
case the laser diode driver IC 3 could be eliminated. Also, the
invention is not limited with respect to the types of laser diodes
that are used. Laser diodes other than VCSELs may be used for this
purpose. The invention also is not limited with respect to the
types or quantity of components that are mounted on the mounting
device 10.
[0031] In the embodiment shown in FIG. 1, monitor photodiodes 7 are
integrated into the laser diode driver ICs 2 and 3. These monitor
photodiodes 7 monitor the optical output levels of respective ones
of the laser diodes 5 and produce corresponding electrical signals
that are fed back to control logic (not shown), which uses the
feedback to adjust the electrical control signals that are
delivered by the laser diode driver ICs 2 and 3 to the VCSEL IC 4.
These control signals cause the bias and/or modulation currents of
the laser diodes 5 to be adjusted such that the average optical
output power levels of the laser diodes 5 are maintained at
substantially constant predetermined levels. The increased pitch
between the high-speed signal paths provided by the balanced driver
layout shown in FIG. 1 enables the monitor photodiodes 7 to be
integrated into the laser diode driver ICs 2 and 3. Integrating the
monitor photodiodes 7 into the laser diode driver ICs 2 and 3
eliminates the need to provide a separate monitor photodiode IC in
the transmitter 1 for monitoring the optical output power levels of
the laser diodes 5. Eliminating the need for a separate monitor
photodiode IC results in a more efficient utilization of space in
the optical transmitter 1, thereby enabling the transmitter 1 to be
reduced in size relative to the aforementioned known parallel
optical transmitters. In addition, eliminating the need for a
separate monitor photodiode IC also results in fewer wire bonds and
pin connections, which reduces circuit complexity, power
consumption, electrical cross-talk, and inductive coupling.
However, the monitor photodiodes 7 are optional and are not
required by the parallel optical communications device of the
invention.
[0032] The mounting device 10 has a lower surface 10B that is
attached to an upper surface 20A of the substrate 20 with an
adhesive material, such as an epoxy, an adhesive tape or solder,
for example. The substrate 20 is a circuit board of some type, such
as a PCB, for example. The substrate 20 has electrical conductors
(not shown) and electrical vias (not shown) extending through it
and electrical contacts (not shown) on its upper surface 20A. The
electrical contacts (not shown) on the upper surface 20A of the
substrate 20 are electrically coupled via electrically conductive
bond wires 26 to electrical contact pads 28 on the laser diode
driver ICs 2 and 3. The lower surface 20B of the substrate 20 has
an array of electrically conductive contact pads (not shown)
thereon that electrically couple to an array (not shown) of
electrically conductive contact pads located on a motherboard (not
shown). The motherboard (not shown) typically has a controller IC
(not shown) mounted on it that communicates with the laser diode
driver ICs 2 and 3 of the ESA 1.
[0033] As will be described below in more detail with reference to
FIG. 4, in accordance with this illustrative embodiment, the
mounting device 10 has tabs (10C in FIG. 4) that protrude outwardly
near the corners of the mounting device 10. The tabs are shaped and
sized to mate with complementary indentations (not shown) formed in
the first and second bond wire protector devices 30A and 30B of the
bond wire protector 30. This mating configuration enables the bond
wire protector devices 30A and 30B to be passively aligned with and
mechanically coupled to the mounting device 10. When the bond wire
protector devices 30A and 30B are in engagement with the mounting
device 10, a gap exists between the bond wire protector devices 30A
and 30B and the side edges of the mounting device 10 within which
the bond wires 26 extend between the contacts on the substrate 20
and the contact pads 28 on the laser diode driver ICs 2 and 3. This
gap ensures that the bond wire protector devices 30A and 30B do not
come into contact with the bond wires 26 and damage them. The bond
wire protector devices 30A and 30B protect the bond wires 26 from
external forces that can potentially damage the bond wires 26, such
as mechanical handling forces that occur during the manufacturing
and assembling of the parallel optical transmitter. It should be
noted, however, that the bond wire protector 30 is optional. Other
methods and mechanisms may be used to protect the bond wires 26.
For example, a method known as glob topping may be used to protect
the bond wires 26.
[0034] In accordance with the illustrative embodiment depicted in
FIG. 1, the mounting device 10 has an upper portion 10D that
includes the upper surface 10A of the device 10, and a lower
portion 10E that includes the lower surface 10B of the mounting
device 10. With reference to the X, Y, Z Cartesian coordinate
reference shown on the drawing page that contains FIG. 1, the
length of the upper portion 10D in the X direction is greater than
the length of the lower portion 10E in the X direction. The
mounting device 10 is typically made of a material that has a high
thermal conductivity, such as copper plated with nickel or gold,
for example, to enable the device 10 to function effectively as a
heat dissipation structure. Heat generated by the ICs 2, 3 and 4
passes down into the mounting device 10 and is spread into the
mounting device 10. Making the upper portion 10D of the mounting
device 10 large in the X direction increases the amount of surface
area on the upper surface 10A that is available for sinking
heat.
[0035] Because the material that is used to make the mounting
device 10 is also electrically conductive, if the mounting device
10 is too close to the signal pathways (not shown) in the substrate
20, the mounting device 10 can couple capacitance into the
substrate 20 that increases the capacitance of the signal pathways
in the substrate 20. This increased coupling capacitance can
degrade signal quality. This is especially true for the high speed
signal pathways (not shown), such as those that carry the
electrical data signals that are used to modulate the laser diodes
5 of the VCSEL IC 4. In accordance with this illustrative
embodiment, the lower portion 10E of the mounting device 10 is made
smaller than the upper portion 10D in the X direction to ensure
that the lower surface 10B has a relatively small surface area
compared to the upper surface 10A, thereby reducing the coupling
capacitance contributed by the mounting device 10 to the substrate
20.
[0036] In order to further reduce the effect of coupling
capacitance, the high speed signal pathways (not shown) in the
substrate 20 may be routed such that they are never contained in
the portion of the upper surface 20A of the substrate 20 that is
directly below the lower portion 10E of the mounting device 10. To
accomplish this, the high speed signal pathways may be either
routed around this region where the lower surface 10B of the
mounting device 10 attaches to the upper surface 20A of the
substrate 20, or routed in lower layers of the substrate 20 that
are farther away from the lower surface 10B of the mounting device
10 in this region.
[0037] While the shape of the mounting device 10 described above
provides the advantages described above, it is not necessary for
the mounting device 10 to have this type of configuration. For
example, the mounting device 10 could have a planar configuration
with the upper and lower surfaces 10A and 10B having the same
lengths in the X direction. Alternatively, the mounting device may
have a tapered configuration, as will be described below in more
detail with reference to FIG. 4.
[0038] The upper portion 10D of the mounting device 10 has slots 40
formed therein at opposing ends of the mounting device 10. Each of
the slots 40 contains a weldable insert 50. The weldable inserts 50
are used to weld the ESA 1 to the OSA (not shown), as will be
described below in detail with reference to FIGS. 2A and 2B. The
weldable inserts 50 are made of a material such as, for example,
stainless steel SUS 316 or 304, although the invention is not
limited to using any particular type of weldable material for the
inserts 50. The inserts 50 may be secured within the slots 40 by a
variety of methods, including, for example, push fitting the
inserts 50 into the slots 40 such that the inserts are held within
the slots 40 by a friction fit, and brazing the inserts 50 to the
slots 40.
[0039] FIGS. 2A and 2B illustrate perspective top and bottom views,
respectively, of the OSA 60 of the parallel optical communications
device accordance with an embodiment. The OSA 60 includes a lens
holder 70 and a heat dissipation system 80. In accordance with this
embodiment, the heat dissipation system 80 comprises first and
second heat dissipation blocks 80A and 80B, which are secured to
features 71 on opposing sides of the lens holder 70. The heat block
80A has an upper surface 80C and a lower surface 80D. Likewise, the
heat dissipation block 80B has an upper surface 80E and a lower
surface 80F. Each of the heat dissipation blocks 80A and 80B has a
slot 90 formed in the lower surface 80D and 80F, although only the
slot 90 formed in the lower surface 80D of block 80A is visible in
the view shown in FIG. 2A.
[0040] As can be seen in FIG. 2B, each of the slots 90 has a
weldable insert 100 secured in it. The weldable inserts 100 may be
secured in the slots 90 using any of the methods described above
for securing the weldable inserts 50 in the slots 40 formed in the
mounting device 10 (FIG. 1). The weldable inserts 100 may be made
of the same material as the weldable inserts 50. The lens holder 70
holds an optic 75 that has a plurality of optical elements 77 for
optically coupling light between a respective one of the laser
diodes 5 and an end of a respective optical waveguide (not
shown).
[0041] FIG. 3 illustrates a perspective top view of the parallel
optical transmitter 110 of the invention in accordance with an
illustrative embodiment, which shows the transmitter 110 after the
OSA 60 shown in FIGS. 2A and 2B has been secured to the ESA 1 shown
in FIG. 1. The manner in which the OSA 60 is secured to the ESA 1
will now be described with reference to FIGS. 1-3. In order to
secure the OSA 60 to the ESA 1, the OSA 60 is placed in contact
with the ESA 1 such that the weldable inserts 50 of the ESA 1 are
in contact with the respective weldable inserts 100 of the OSA 60.
The lens holder 70 has an aperture 78 formed therein through which
light generated by the laser diodes 5 to be directed by the
respective optical elements 77 onto ends of respective optical
waveguides (not shown) that are held within a connector (not shown)
that mechanically couples with the OSA 60. After the OSA 60 has
been placed in contact with the ESA 1, a vision system (not shown)
captures an image of the laser diodes 5 and of the optical elements
77 and a motion system (not shown) or a person moves one or both of
the OSA 60 and the ESA 1 until the respective laser diodes 5 are
precisely optically aligned with the respective optical elements
77. Once optical alignment has been achieved, the OSA 60 and the
ESA 1 are held tightly in the aligned position while the weldable
inserts 50 and 100 are welded together at one or more locations on
the inserts 50 and 100.
[0042] There are many advantages to welding the ESA 1 and the OSA
60 together. One advantage is that the weld forms a welded joint
between the ESA 1 and the OSA 60 that is structurally extremely
strong. The structural strength of this joint ensures that there
will be no movement of the OSA 60 and of the ESA 1 relative to each
other, which ensures that the precise optical alignment of the
optical elements 77 with the respective laser diodes 5 will not be
compromised over the entire lifetime of the parallel optical
transmitter 110. As mentioned above, forces are often exerted on
the transmitter after it has been manufactured, and the welded
joint is strong enough to withstand these forces. For example, the
customer will typically attach an external heat dissipation system
(not shown) to the heat dissipation blocks 80A and 80B, and the
attachment process can result in large forces (e.g., 20 lbs) being
exerted on the OSA 60. The welded joint is sufficiently strong to
withstand such forces, even if any of this force includes a lateral
component that is maintained permanently after the external heat
dissipation system has been attached.
[0043] Another advantage of welding the ESA 1 to the OSA 60 in the
manner described above is that the size of the slots 40 and 90 is
relatively small compared to the total surface area of the upper
surface 10A of the mounting device 10 and of the lower surfaces 80D
and 80F of the heat dissipation blocks 80A and 80B. The material of
which the inserts 50 and 100 are made is typically a material of
relatively low thermal conductivity, which is not well suited for
dissipating heat. On the other hand, the material of which the
mounting device 10 and the heat dissipation blocks 80A and 80B are
made (e.g., copper) has a very high thermal conductivity.
Therefore, it is desirable to maximize the amount of area of the
upper surface 10A of the mounting device 10 that is in contact with
the lower surfaces 80D and 80F of the heat dissipation blocks 80A
and 80B, respectively. By embedding the inserts 50 and 100 in
relatively small slots 40 and 90 formed in the surfaces 10A, 80D
and 80F, most of the areas of these opposing surfaces are in
contact with one another once the inserts 50 and 100 have been
welded together. For example, the percentage of the respective
surface areas of the lower surfaces 80D and 80F that the slots 90
consume is less than about 50%, and typically less than about 35%.
For example, while the slots 40 and 90 typically have the about the
same width as that of the heat dissipation blocks 80A and 80B, the
length of the lower surfaces 80D and 80F of the blocks 80A and 80B
may be about 5.0 millimeters (mm), whereas the length of the slots
40 and 90 may be only about one-third of that, or about 1.6 mm.
These features provide the parallel optical communications device
with very good heat dissipation characteristics, and thus very high
thermal performance, which, as indicated above, is very important
in parallel optical communications devices that communicate high
speed signals over a plurality of transmit and/or receive
communications channels.
[0044] FIG. 4 illustrates a top perspective view of the mounting
device 10 shown in FIG. 3. As mentioned above, the mounting device
10, in accordance with an embodiment, has four tabs 10C on its
sides near its corners. These tabs 10C are configured to mate with
complementary indentations (not shown) on the bond wire protector
30 (FIG. 1) to prevent, or at least reduce, relative movement
between the mounting device 10 and the bond wire protector 30. The
view shown in FIG. 4 allows the shape of the slots 40 and of the
inserts 50 to be clearly seen. In accordance with an illustrative
embodiment, the slots 40 and the inserts 50 are rectangular in
shape, although the invention is not limited to the slots 40 and
the inserts 50 having any particular shapes or sizes. In accordance
with an embodiment, the mounting device 10 has slots 10G and 10H
formed therein that provide air gaps between the location at which
the laser diode IC 2 is mounted (in between the slots 10G and 10H)
and the locations at which the laser diode driver ICs 3 and 4 are
mounted. The air gaps thermally isolate the laser diode IC 2 from
the driver ICs 3 and 4 to prevent heat from the laser driver ICs
from detrimentally affecting the laser diodes 5 of the laser diode
IC 2. The slots 10G and 10H are optional, but preferred, as they
assist with the overall heat dissipation design of the parallel
optical transmitter.
[0045] FIG. 5 illustrates an exploded view of a portion of the side
of the parallel optical transmitter 110 shown in FIG. 3. In the
exploded view, a portion of the substrate 20, the mounting device
10, and the side 71 of the lens holder 70 of the OSA 60 can be
seen. Within the exploded view, the slots 40 and 90 and their
respective inserts 50 and 100 can also be seen. In accordance with
an embodiment, the slots 50 of the mounting device 10 are slightly
greater in the length, L, dimension than the slots 90 of the OSA
60. The inserts 50 are slightly greater in both the length, L, and
width, W dimensions. This difference between the dimensions of the
slots 40 and 90 and of the inserts 50 and 100, respectively,
results in steps 130 at the interfaces of the inserts 50 and 100.
These steps 130 provide space for the welds to form when the
inserts 50 and 100 are welded together, rather than forming on two
flush faces of the opposing inserts 50 and 100. This feature
improves the integrity of the welded joint. The step 130 is not
necessary, as the welded joint should have sufficient strength even
if the weld is formed on the flush opposing faces of the inserts 50
and 100, as will be understood by those of ordinary skill in the
art in view of the description being provided herein. The step 130
is merely one way to further ensure that the resulting welded joint
is extremely strong. Also, the step 130 could instead be formed by
making the slots 90 slightly greater in the width dimension that
the slots 40 and by making the inserts 100 slightly greater in the
width and length dimensions that the inserts 50.
[0046] FIG. 6 illustrates a perspective bottom view of the heat
dissipation block 80B of the parallel optical transmitter 110 shown
in FIG. 3 in accordance with an embodiment. In accordance with this
embodiment, the weldable inserts 50 and/or 100 may have resistive
features on them to allow for resistive welding to be used to weld
the inserts 50 and 100 together. In FIG. 6 the inserts 100 that are
contained in slots 90 formed in the heat dissipation blocks include
one or more of such resistive features 140. When using this type of
welding technique, an electrical current is passed through the
inserts 100. The resistive features 140 locally increase the
electrical resistance encountered by the electrical current,
causing the resistive features to melt and fuse to the inserts 50
contained in the slots 40 of the mounting device 10. For ease of
illustration and in the interest of brevity, only the inserts 100
of the OSA 60 are shown in FIG. 6 as containing the resistive
features 130. The resistive features 130 could instead be contained
in the inserts 50 of the mounting device 10, or could be contained
in both the inserts 50 and the inserts 100.
[0047] FIG. 7 illustrates an exploded view of a portion of the side
of the parallel optical transmitter 110 shown in FIG. 3. In the
exploded view, a portion of the substrate 20, the mounting device
10, and the side 71 of the lens holder 70 of the OSA 60 can be
seen. Within the exploded view, the slots 40 and 90 and their
respective inserts 50 and 100 can also be seen. In accordance with
an embodiment, like the embodiment described above with reference
to FIG. 5, there is a difference between the dimensions of the
slots 40 and 90 and of the inserts 50 and 100, respectively, which
results in the aforementioned steps 130 existing at the interfaces
of the inserts 50 and 100. This step 130 provides space for a
solder material 150 to be located. When an electric current is
passed through the solder material 150, the solder material 150
melts. Once the solder material 150 re-solidifies, the
re-solidified solder material 150 forms the welded joint that holds
the ESA 1 and the OSA 60 together.
[0048] FIG. 8 illustrates a perspective view of a cross-section of
the parallel optical transmitter 110 shown in FIG. 3. In the view
shown in FIG. 8, a portion of the substrate 20, the mounting device
10, the side portions 71 of the lens holder 70, and overlapping
portions of the inserts 50 and 100 to form the step 130 can be
seen. In accordance with this embodiment, a well known laser
welding technique is used to locally heat areas 160 where the
inserts 50 and 100 meet. When these areas 160 are heated, they heat
up rapidly, and then cool. As the areas 160 cool, the inserts 50
and 100 become fused together to form the welded joint. When the
laser welding technique is properly performed, the welded joint
that is formed is extremely strong. In addition, because laser
welding can be performed very quickly, using this technique to form
the welded joint expedites the process of optically aligning the
ESA 1 and the OSA 60 and forming the welded joint that holds them
together. Areas in addition to the areas 160 may be heated with the
laser, such as additional areas along the step 130 where the
inserts 50 and 100 meet.
[0049] It should be noted that the invention is not limited to a
parallel optical transmitter 110. Although the invention has been
described with reference to the parallel optical transmitter 110,
the parallel optical communications device may instead be a
parallel optical receiver or a parallel optical transceiver. In the
case of a parallel optical receiver, the laser diodes 5 would be
replaced with photodiodes (not shown) and the laser diode driver
ICs 3 and 4 would be replaced with a receiver IC (not shown), as
will be understood by persons of ordinary skilled in the art. The
OSA 60 may be configured the same for a parallel optical receiver.
In the case of a parallel optical transceiver, half of the active
optical devices may be laser diodes and the other half of the
active optical devices may be photodiodes. The OSA 60 may be
configured the same for a parallel optical transceiver. Thus, the
term "a parallel optical communications device", as that term is
used herein, is intended to denote a parallel optical transmitter,
a parallel optical receiver, or a parallel optical transceiver.
[0050] It should be noted that the invention has been described
with respect to illustrative embodiments for the purpose of
describing the principles and concepts of the invention. The
invention is not limited to these embodiments. For example, while
the invention has been described with reference to using a
particular balanced driver layout, the invention is not limited to
this particular layout. Also, while the invention has been
described with reference to a particular configuration for the
slots 40 and 90 and for the respective weldable inserts 50 and 100,
the invention is not limited to this particular configuration. The
invention also is not limited to using any particular welding
technique to create the welded joint, as will be understood by
persons of ordinary skill in the art in view of the description
being provided herein. As will be understood by those skilled in
the art in view of the description being provided herein, many
modifications may be made to the embodiments described herein while
still providing a parallel optical communications device that
achieves the goals of the invention, and all such modifications are
within the scope of the invention.
* * * * *